The long-term goal of this research project is to acquire a more complete understanding of the relation of structure to function in pituitary growth hormone (GH). Peptides will be derived from peptides 1-134, 135-191 and 141-191 of human GH (hGH) by various enzymatic and chemical means. The activities of these peptide fragments will be assessed in a variety of biological assays that test for the anabolic, insulinlike, diabetogenic and lactogenic activities of hGH and in radioimmunological and radioreceptor assays. Attempts will then be made to recombine noncovalently these fragements of the N- and C-terminal portions of the hGH molecule. The recombinant hGH molecules will then be tested for activities in the above assays. An effort will also be made to produce hybrid GH recombinants by combining fragments of hGH with fragments of porcine GH, in order to gain some insight into the structural basis for species specificity of the growth hormone.